Research On Ku-band Transmitter Front-end Chip Based On SiGe BiCMOS Process

In the information society,microwave technology has been widely used in information communication,radar detection,medical detection and other technical fields.The point-to-point,point-to-surface,and multipoint transmission of these telecommunications signals has always been inseparable from transmitting and receiving.The process,especially the transmission stage,is the most important.This stage directly determines the transmission frequency and transmission power,and then determines the quality of the signal at the beginning of propagation,and whether it can be captured by the receiving end after space propagation.Therefore,the research on the front-end chip of the transmitter is of great significance to improve the transmission rate and quality of information.At present,the mainstream technologies of transmitter front-end chips are GaAs,GaN,and silicon-based.However,GaAs and GaN materials are expensive to process and difficult to communicate with other modules in the transmission link,such as upstream digital signal processing modules,and The downstream communication chip or other digital and analog circuit modules are highly integrated,which makes the transmitter chip costly and the area too large,which is difficult to meet the low-cost and miniaturized market demand in modern applications.The silicon-based process has a metal layer It has many features,such as convenient wiring,low processing cost,and easy integration with digital circuits.Its market share continues to increase.This research is based on the GF 0.13?m SiGe BiCMOS process,in order to address how the transmitter's front-end chip can achieve 100% ultra-wide relative operating bandwidth,high gain,good in-band gain flatness,good high and low temperature gain fluctuations,and image frequency suppression.A passive Marchand balun type mixer with Cascode structure amplifier is used.The mixer uses a tail LC tuning branch.The amplifier uses a temperature-compensated current mirror,a negative resistance generation circuit,and an RC branch negative feedback.Technology,research and design a front-end chip for ultra-wideband transmitter.The main tasks are as follows:1.Aiming at the difficulty that the relative operating bandwidth of the intermediate frequency signal(1 ~ 3GHz)reaches 100%,the structure of the double-balanced mixer covers an excessively wide frequency band,and the tail LC tuning technology is used to adjust the frequency of the passive mixer.In the face of excessive loss,the IF and local oscillator signals are leaking like radio frequency ports.After simulation,the frequency conversion loss of-6.3dB,the flatness of the in-band gain of 2dB,and the port isolation above-40 dB are achieved at room temperature.2.Aiming at the problem that the conversion loss of the mixer module is more sensitive to the port impedance of the amplifier with which it is matched,this article analyzes and compares the common common-radiation stage and common-base-stage amplifier structure,and finally based on the Cascode structure,using Technologies such as temperature compensated current mirror,negative resistance generation circuit,and RC branch negative feedback design IF and RF amplifiers respectively,and have obtained the advantages of high gain,broadband matching,and high reverse isolation.After simulation,the IF amplifier can provide 10.6 at room temperature.dB gain,OP1 dB can reach 10.7dBm;IF amplifier can provide 13.7dB gain,OP1 dB can reach 13.34 dBm.3.The whole transmitter chip was cascading simulated and tested successfully.The simulation results showed that the whole transmitter had a gain of 19 dB and max OP1 dBout of 12 dBm.The test results show that the transmitter as a whole has a gain of 17 dB and max OP1 dBout of 7dBm.For the differences between the simulation and test results,the analysis lists the possible reasons that the AC grounding performance during the dicing and assembly process will reduce the gain of the single-ended amplifier Degradation of performance such as linearity and linearity;feasible improvement solutions are given,such as the use of differential structure amplifiers that are not sensitive to AC grounding performance to avoid the impact of dicing and assembly processes on chip grounding performance.4.Aiming at the problem that the image frequency generated during the mixing process overlaps with the ideal useful frequency band,this paper proposes a scheme for IQ synthesis to suppress the image,which perfectly solves the problem of image frequency suppression.